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The author is drastically overestimating the lifecycle emissions and embodied energy of modern solar photovoltaic modules. The article claims that it takes "3,

The author is drastically overestimating the lifecycle emissions and embodied energy of modern solar photovoltaic modules. The article claims that it takes "3,514 MJ of energy to produce one m2 of solar panel." The source for that assertion is this article from 2017: "Energy Payback Time of a Solar Photovoltaic PoweredWaste Plastic Recyclebot System" https://www.e-helvetica.nb.admin.ch/api/download/urn%3Anbn%3Ach%3Abel-1002434%3Arecycling-02-00010.pdf/recycling-02-00010.pdf https://www.e-helvetica.nb.admin.ch/api/download/urn%3Anbn%3... That article cites this article from 2006 as its source for energy intensity of solar manufacturing: "Embodied energy analysis of photovoltaic (PV) system based on macro- and micro-level" https://sci-hub.tw/10.1016/j.enpol.2005.06.018 https://sci-hub.tw/10.1016/j.enpol.2005.06.018 That publication finds that silicon purification and processing accounts for the lion's share of embodied energy in solar PV. But if you read section 6 of the paper, "Embodied energy of silicon purification and processing", you see that those authors are using material production energy intensity numbers from 2004 and 1998. They are also assuming the use of electronic grade silicon for solar manufacturing, and a silicon requirement of 12 grams per watt-peak of solar module. Cheaper and less energy intensive solar grade silicon has entirely replaced electronic grade silicon in PV since the early 2000s. Modern solar module silicon use is about 3 grams per watt-peak, not 12; see Table 1 in https://pubs.rsc.org/en/content/articlehtml/2020/ee/c9ee02452b https://pubs.rsc.org/en/content/articlehtml/2020/ee/c9ee0245.... What first appears to be a reasonably recent citation for PV embodied energy is actually a chain of painfully outdated assumptions going all the way back to the 1990s.

lowtechmagazine 7y ago
Author here. Good you mention this. I could have chosen a more elegant citation, but data on the embodied energy of PV modules is generally outdated and confusing. The number I chose is not especially high for panels produced since the 2000s. For an extensive literature summary from 2011 see 2.3 http://www.seas.columbia.edu/clca/Task12_LCI_LCA_10_21_Final_Report.pdf http://www.seas.columbia.edu/clca/Task12_LCI_LCA_10_21_Final... Also keep in mind that all the panels we tested are much smaller than the ones oin those studies. This means that things like the frame, wires, connections become more important for embodied energy.
- philipkglass 7y ago
  That study is also badly outdated. Under section 5, Life Cycle Inventory Data, it says "The authors have assembled this LCI data set to the best of their knowledge and in their opinion it gives a reliable representation of the crystalline silicon module production technology in Western-Europe in the year 2005/2006 and Balance-of-System components of the year 2006." I would love to see a life cycle assessment using wholly up-to-date numbers. I keep reading new studies on PV LCA, energy return on investment, and/or energy payback time. People who write these sorts of papers don't seem to keep up with what industry is actually doing. You can learn a lot from data sheets and trade publications. E.g. from published glass thickness and module size and efficiency, you can calculate the quantity of glass currently needed per watt-peak. It's significantly lower than any of these studies using decade+ outdated numbers. I think part of the problem is one of incentives. Academics writing about LCA are often comparing some hoped-to-be-up-and-coming technology against the mainstream. Like thin film PV, organic PV, or dye sensitized cells pitted against crystalline silicon PV. In that case using old numbers for silicon PV helps the newer technology look like it offers exciting improvements. Another problem is that reviewers apparently don't care very much about these temporal effects. They don't chase the citation chains to find the really outdated measurements cited in recently submitted manuscripts. Another problem is that the solar industry has grown large and competitive. Cutting-edge numbers about energy consumption for silicon refinement are probably retained as a competitive advantage by the biggest producers, for example. It's possible to set tighter upper bounds on resource intensity just from teardowns of recently manufactured modules. I suppose that teardown based analysis may itself be the sort of information you only get from specialty publications like the Photovoltaics International magazine, which is expensive and not indexed by DOI or part of ordinary academic libraries. (So it's not even in sci-hub.) It's $599 a year if you want to be able to read back issues of Photovoltaics International from their archives: https://store.pv-tech.org/photovoltaics-international/ https://store.pv-tech.org/photovoltaics-international/ I am interested enough in photovoltaic technology that I have bought a couple of $100+ specialty books from academic publishers, but $599 is a bit too steep even for me.
  - lowtechmagazine 7y ago
    The obsolescence of life cycle analyses is a topic in itself, and the lack of accessible data is a problem for anyone who tries to investigate high-tech products. For the solar powered website article, it's the order of magnitude that matters. You say I overestimate the energy use of solar panel production, but in our configuration it corresponds to just 1 liter of oil per year.
beerandt 7y ago
LCAs are sort of the epitome of "looks a lot easier than it is," combined with no obvious red flags for getting something drastically wrong. Mistakes like these are everywhere. And I'm afraid the average study quality is going to get a lot worse before it gets better. A little bit of knowledge can be a dangerous thing. At least we're not making many safety critical design decisions based off of them, yet.
graycat 7y ago
So, yup, we need at least old common high school term paper writing standards, e.g., support every claim with good references to high quality, credible, primary sources. And, of course, as you mention, give the darned dates. Ah, maybe a lot of media content would be seen right away of no interest if those standards had been followed. Or, about news writing, in some old movies, "If it's not good, I'll make it good." and "A good reporter doesn't get great stories. A good reporter makes them great." Now from that and not being born recently, I have learned to avoid nearly all news media.
- lowtechmagazine 7y ago
  It's a bit more complex than that. The life cycle analysis of high-tech products takes many years. That's why most studies seem to be outdated even right after they are just published. It's not just solar panels. Try looking for a life cycle analysis of a recent laptop.

lowtechmagazine 7y ago

Author here. Good you mention this. I could have chosen a more elegant citation, but data on the embodied energy of PV modules is generally outdated and confusing. The number I chose is not especially high for panels produced since the 2000s. For an extensive literature summary from 2011 see 2.3 http://www.seas.columbia.edu/clca/Task12_LCI_LCA_10_21_Final_Report.pdf http://www.seas.columbia.edu/clca/Task12_LCI_LCA_10_21_Final... Also keep in mind that all the panels we tested are much smaller than the ones oin those studies. This means that things like the frame, wires, connections become more important for embodied energy.

philipkglass 7y ago
That study is also badly outdated. Under section 5, Life Cycle Inventory Data, it says "The authors have assembled this LCI data set to the best of their knowledge and in their opinion it gives a reliable representation of the crystalline silicon module production technology in Western-Europe in the year 2005/2006 and Balance-of-System components of the year 2006." I would love to see a life cycle assessment using wholly up-to-date numbers. I keep reading new studies on PV LCA, energy return on investment, and/or energy payback time. People who write these sorts of papers don't seem to keep up with what industry is actually doing. You can learn a lot from data sheets and trade publications. E.g. from published glass thickness and module size and efficiency, you can calculate the quantity of glass currently needed per watt-peak. It's significantly lower than any of these studies using decade+ outdated numbers. I think part of the problem is one of incentives. Academics writing about LCA are often comparing some hoped-to-be-up-and-coming technology against the mainstream. Like thin film PV, organic PV, or dye sensitized cells pitted against crystalline silicon PV. In that case using old numbers for silicon PV helps the newer technology look like it offers exciting improvements. Another problem is that reviewers apparently don't care very much about these temporal effects. They don't chase the citation chains to find the really outdated measurements cited in recently submitted manuscripts. Another problem is that the solar industry has grown large and competitive. Cutting-edge numbers about energy consumption for silicon refinement are probably retained as a competitive advantage by the biggest producers, for example. It's possible to set tighter upper bounds on resource intensity just from teardowns of recently manufactured modules. I suppose that teardown based analysis may itself be the sort of information you only get from specialty publications like the Photovoltaics International magazine, which is expensive and not indexed by DOI or part of ordinary academic libraries. (So it's not even in sci-hub.) It's $599 a year if you want to be able to read back issues of Photovoltaics International from their archives: https://store.pv-tech.org/photovoltaics-international/ https://store.pv-tech.org/photovoltaics-international/ I am interested enough in photovoltaic technology that I have bought a couple of $100+ specialty books from academic publishers, but $599 is a bit too steep even for me.
- lowtechmagazine 7y ago
  The obsolescence of life cycle analyses is a topic in itself, and the lack of accessible data is a problem for anyone who tries to investigate high-tech products. For the solar powered website article, it's the order of magnitude that matters. You say I overestimate the energy use of solar panel production, but in our configuration it corresponds to just 1 liter of oil per year.

beerandt 7y ago

LCAs are sort of the epitome of "looks a lot easier than it is," combined with no obvious red flags for getting something drastically wrong. Mistakes like these are everywhere. And I'm afraid the average study quality is going to get a lot worse before it gets better. A little bit of knowledge can be a dangerous thing. At least we're not making many safety critical design decisions based off of them, yet.

graycat 7y ago

So, yup, we need at least old common high school term paper writing standards, e.g., support every claim with good references to high quality, credible, primary sources. And, of course, as you mention, give the darned dates. Ah, maybe a lot of media content would be seen right away of no interest if those standards had been followed. Or, about news writing, in some old movies, "If it's not good, I'll make it good." and "A good reporter doesn't get great stories. A good reporter makes them great." Now from that and not being born recently, I have learned to avoid nearly all news media.

lowtechmagazine 7y ago
It's a bit more complex than that. The life cycle analysis of high-tech products takes many years. That's why most studies seem to be outdated even right after they are just published. It's not just solar panels. Try looking for a life cycle analysis of a recent laptop.